JP7552255B2 - Reading device, image forming device and method - Google Patents

Description

The present invention relates to a reading device, an image forming device, and a method.

Conventionally, there is known technology for image reading devices that simultaneously irradiate an original with visible light and near-infrared light, and simultaneously read an image based on visible light and an image based on near-infrared light in a single scanning operation. When visible light and near-infrared light are irradiated simultaneously onto an original, they may be detected if the original is sensitive to light from the other light source other than the wavelength to be read. In such cases, the light from the other light source is superimposed on the output image from the sensor, causing color mixing, so technology has also been disclosed that adjusts the amount of light to suppress color mixing.

For example, Patent Document 1 discloses a technology for calculating the degree of color mixing of the sensor for each light source and adjusting the amount of light using the calculation results in an image reading device that reads images by simultaneously turning on light sources of different wavelength bands.

However, there was a problem in that suppressing color mixing required an increased amount of memory to adjust the light intensity.

The present invention has been made in consideration of the above, and aims to provide a reading device, an image forming device, and a method that can reduce the amount of memory required for adjusting the amount of light and suppress color mixing.

In order to solve the above-mentioned problems and achieve the object, the reading device of the present invention is characterized in comprising: a first light source; a second light source having a light wavelength different from that of the first light source; an instruction means for instructing turning on and off the first light source and the second light source; a first light amount adjustment means for adjusting the light amount of the first light source based on a first light amount value; a second light amount adjustment means for adjusting the light amount of the second light source based on a second light amount value ; a first image sensor for receiving light of the first light source reflected from a subject; a second image sensor for receiving light of the first light source and light of the second light source reflected from the subject; and a setting means for setting a light amount value that satisfies a first light amount condition based on output data output from the first image sensor when the first light source is turned on as the first light amount value, and setting a light amount value that satisfies a second light amount condition based on output data output from the second image sensor when the first light source is turned on as the second light amount value.

The present invention has the effect of reducing the amount of memory required for adjusting the light intensity and suppressing color mixing.

FIG. 1 is a diagram illustrating an example of a reading device according to a first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a processing unit that adjusts the amount of light in the reading device. FIG. 3 is a diagram showing an example of the configuration of a light source and an image sensor. FIG. 4 is a flow diagram showing an example of a first pattern of light amount adjustment of the reading device. FIG. 5 is a flow diagram showing an example of the second pattern of light amount adjustment of the reading device. FIG. 6 is a flow diagram showing an example of the third pattern of light amount adjustment of the reading device. FIG. 7 is a flow diagram showing an example of the fourth pattern of light amount adjustment of the reading device. FIG. 8 is a diagram showing an example of a document. FIG. 9 is a comparison diagram of output images of the image sensor that read an original when the maximum light amount that does not cause saturation is set and when it is not set. FIG. 10 is a diagram showing an example of the configuration of a processing unit that adjusts the amount of light in the reading device according to the first embodiment. FIG. 11 is a comparative diagram showing a document to be read and an output image output from an image sensor by reading the document image once. FIG. 12 is a diagram illustrating an example of the configuration of a processing unit that adjusts the amount of light in the reading device according to the first modification. FIG. 13 is a flow diagram showing an example of light amount adjustment of the reading device. FIG. 14 is a comparative diagram showing a document to be read and an output image output from an image sensor by reading the document image once. FIG. 15 is a diagram showing an example of a certificate in which two-dimensional code information is used as invisible information. FIG. 16 is a flow diagram illustrating an example of light amount adjustment of the reading device according to the second modification. FIG. 17 is a diagram showing an example of a certificate in which one-dimensional barcode information is used as invisible information. FIG. 18 is a flow diagram illustrating an example of light amount adjustment of the reading device according to the third modification. FIG. 19 is a diagram illustrating an example of the configuration of a processing unit that adjusts the amount of light in a reading device according to the fourth modification. FIG. 20 is a comparative diagram showing a document to be read and an output image output from an image sensor by reading the document image once. FIG. 21 is a diagram showing an example of the configuration of a processing unit that adjusts the amount of light in a reading device when a general-purpose image sensor is used. FIG. 22 is a diagram showing the spectral characteristics of a silicon image sensor. FIG. 23 is a diagram showing an example of a configuration including a reference subject. FIG. 24 is a diagram illustrating an example of a configuration of an image forming apparatus according to the second embodiment. As illustrated in FIG.

Embodiments of the reading device, image forming device and method will be described in detail below with reference to the attached drawings. Note that in the following, the term "visible" refers to the wavelength range of visible light (visible wavelength range), and "invisible" refers to wavelength ranges other than visible light such as infrared and ultraviolet light. Examples of invisible wavelength ranges (invisible wavelength ranges) include 380 nm or less or 750 nm or more. In the following, a document or the like is shown as an example of an "object," but during periods when the document or the like is not being read, a member (reference member, etc.) at the reading position of the document corresponds to the object. An example is shown in which light from a light source is reflected by the object and enters an image sensor.

(First embodiment)
Fig. 1 is a diagram illustrating an example of a reading device according to a first embodiment of the present invention, in which an automatic document feeder (ADF) is mounted as an example of the reading device.

The reading device body 10 has a contact glass 11 on its top surface, and inside the reading device body 10 are reading means using a reduced optical system, such as a light source 13, a first carriage 14, a second carriage 15, a lens unit 16, and a sensor board 17. In FIG. 1, the first carriage 14 has a light source 13 and a reflecting mirror 14-1, and the second carriage 15 has reflecting mirrors 15-1 and 15-2.

The light source 13 includes a first light source 13a and a first light source 13b, and both the first light source 13a and the first light source 13b are turned on. The first light source 13a and the first light source 13b use light sources with different wavelength bands. For example, the first light source 13a is a light source of light outside the visible wavelength range such as infrared light (called invisible light), and the first light source 13b is a light source of light in the visible wavelength range such as red light (called visible light). Both the light of the first light source 13a and the light of the first light source 13b of the light source 13 are irradiated onto the object to be read, and the reflected light from the object to be read is reflected by the mirror 14-1 of the first carriage 14 and the mirrors 15-1 and 15-2 of the second carriage 15 and enters the lens unit 16, and an image of the object to be read is formed on the light receiving surface on the sensor board 17 from the lens unit 16. The sensor board 17 has a line sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary MOS). The line sensor sequentially converts the light image from the second light source 13b formed on the light receiving surface into electrical signals to output a second image, and sequentially converts the light image from the first light source 13a formed on the light receiving surface into electrical signals to output a first image.

In this embodiment, the reading device 1 simultaneously irradiates the light of the first light source 13a and the light of the second light source 13b onto the reading target. The line sensor captures the irradiated light of the first light source 13a with a first image sensor corresponding to the light of the first light source 13a to output a first image, and captures the irradiated light of the second light source 13b with a second image sensor corresponding to the light of the second light source 13b to output a second image. As an example, if the first light source 13a is infrared light, an IR (infrared) sensor can be used as the first image sensor. Also, if the second light source 13b is visible light, R (Red), G (Green), and B (Blue) image sensors can be used as visible light image sensors.

The reference white board 12 is used to correct changes in the amount of light from the light source 13 and variations in the pixels (pixel circuits) of the line sensor.

The reading device 1 has a control board in the reading device main body 10, and controls each part of the reading device main body 10 and each part of the ADF 20 to read the target object using a specified reading method.

The reading device 1 reads the original 100 using the ADF 20 in a sheet-through manner. In the configuration shown in FIG. 1, the reading device 1 separates the original 100 one by one from the stack of originals on the tray 21 of the ADF 20 using a pickup roller 22, transports the original 100 to a transport path 23, reads the surface of the original 100 to be read at a predetermined reading position, and discharges the original 100 to a paper output tray 25. The original 100 is transported by the rotation of various transport rollers 24.

The reading device 1 reads the original 100, for example, by moving the first carriage 14 and the second carriage 15 to a predetermined home position and fixing them, and while they are fixed, it is performed at the timing when the original 100 passes between the reading window 19 and the background section 26. The reading window 19 is a slit-shaped reading window provided in part of the contact glass 11, and the original 100 is scanned in the sub-scanning direction as it passes through the reading window 19 by automatic transport. The background section 26 is a background member of a predetermined background color that is placed at a position opposite the slit. While the original 100 passes through the reading window 19, the reading device 1 sequentially reads the reflected light of the light from the light source 13 irradiated on the first surface (front or back) of the original 100 facing the reading window 19 with a line sensor on the sensor board 17.

When reading both sides of the document 100, for example, an inversion mechanism that inverts the document from front to back is provided. By providing the inversion mechanism, the reading device 1 can invert the document 100 and read the second side of the document 100 through the reading window 19. Reading may be performed using other configurations, not just an inversion mechanism. For example, after the document 100 passes through the reading window 19, the second side of the document 100 may be read by a reading unit provided on the back side of the document 100. In this case, a white or other member arranged opposite the reading unit corresponds to the background.

In the configuration of the reading device 1 of this example, flatbed reading is also possible. Specifically, the ADF 20 is lifted to expose the contact glass 11, and the original 100 is placed directly on the contact glass 11. Then, the ADF 20 is lowered to its original position and the back side of the original 100 is pressed with the lower part of the ADF 20. In the flatbed method, the original 100 is fixed, so the carriage (first carriage 14, second carriage 15) is moved relative to the original 100 to perform scanning. The first carriage 14 and the second carriage 15 are driven by the scanner motor 18 to scan the original 100 in the sub-scanning direction. For example, the first carriage 14 moves at a speed V, and at the same time, the second carriage 15 moves in conjunction with it at a speed 1/2V, half that of the first carriage 14, to read the first side of the original 100 on the contact glass 11 side. In this case, the lower part of the ADF 20 (a white or other member that holds down the document 100 from the back) corresponds to the background part.

In this example, the first carriage 14, the second carriage 15, the lens unit 16, the sensor board 17, etc. are shown separately, but these may be provided separately or as an integrated sensor module.

In this embodiment, a method of suppressing color mixing that occurs when the light of the first light source 13a is simultaneously irradiated by adjusting the amount of light will be described, taking as an example a case where the light of the second light source is captured using a second image sensor that is sensitive to the wavelength region of the light of the first light source 13b. The second image sensor may also be sensitive to the wavelength region of the light of the first light source 13a. In this case, when the second image sensor is irradiated simultaneously with the light of the first light source 13a, it also detects the light component of the first light source 13a, and the second image sensor outputs a signal on which the light from the first light source 13a is also superimposed, resulting in color mixing in the output image (second image).

Figure 2 is a diagram showing an example of the configuration of a processing unit that adjusts the amount of light in the reading device 1. Figure 2 shows an example of the configuration when a CPU adjusts the amount of light. Figure 2 mainly shows the processing unit and the controlled object related to the light amount adjustment, and does not show other components of the reading device 1.

The CPU 31 is a processor, and controls the entire reading device 1 based on a control program stored in a ROM or the like. In this embodiment, the CPU 31 also performs various processes such as adjusting the light intensity of the first light source 13a and the second light source 13b. For example, the CPU 31 realizes the instruction means 310 and the setting means 311 as functional units by executing a light intensity adjustment program, and adjusts the light intensity of the first light source 13a and the second light source 13b before the document reading process.

The instruction means 310 turns on or off the first light source 13a and the second light source 13b in a predetermined sequence. The setting means 311 acquires output data from the first image sensor 17a and the second image sensor 17b as appropriate, and calculates and sets a light intensity value that satisfies the light intensity condition from the acquired output data.

The CPU 31 sets the light amount value that satisfies the first light amount condition based on the image (first image) that is the output data of the first image sensor 17a as the light amount value (first light amount value) of the first light source 13a. The CPU 31 also sets the light amount value that satisfies the second light amount condition based on the image (second image) that is the output data of the second image sensor 17b as the light amount value (second light amount value) of the second light source 13b.

Memory 32 is a storage unit such as a RAM that CPU 31 uses as a work area. For example, memory 32 is used when CPU 32 temporarily stores data when adjusting the amount of light.

The first light intensity adjustment means 34a adjusts the light intensity of the first light source 13a based on the light intensity value set in the first light intensity setting unit 340a.

The second light amount adjustment means 34b adjusts the light amount of the second light source 13b based on the light amount value set in the second light amount setting unit 340b.

The instruction means 310 and the setting means 311 may be partly or entirely provided in the light amount adjustment means (first light amount adjustment means 34a and second light amount adjustment means 34b). In that case, the light amount adjustment means instructs the first light source 13a and the second light source 13b to be turned on and off, appropriately acquires output data from the first image sensor 17a and the second image sensor 17b, calculates light amount values (first light amount value and second light amount value) that satisfy the respective light amount conditions (first light amount condition and second light amount condition) of the first light source 13a and the second light source 13b, and sets them in each setting unit (first light amount setting unit 340a and second light amount setting unit 340b). In this case, the memory required for light amount adjustment may be provided in the hardware of the light amount adjustment means. In the following, the first light amount condition is described as the light amount condition of the first light source 13a, and the second light amount condition is described as the light amount condition of the second light source 13b.

Figure 3 is a diagram showing an example of the configuration of a light source and an image sensor. Figure 3 shows a schematic diagram of the configuration of the light source and image sensor, the relationship of the arrangement with the object to be read, and the relationship of the incidence of light. As shown in Figure 3, light emitted from the first light source 13a is reflected at the reading position and enters the first image sensor 17a. Light emitted from the second light source 13b is reflected at the reading position and enters the second image sensor 17b. The original 100 is placed at the reading position, and the light emitted from the first light source 13a and the second light source 13b at the reading position causes the reflected light to enter the first image sensor and the second image sensor and be read.

In the example shown in Figure 3, the original 100 is transported by the transport mechanism in the direction of arrow m1, and as it passes the reading position, the light of the first light source 13a is reflected by the original 100 and enters the first image sensor 17a, and the light of the second light source 13b is reflected by the original 100 and enters the second image sensor 17b. However, as shown in Figure 3, the reflected light of the first light source 13a and the second light source 13b also enters the other image sensor (the second image sensor 17b and the first image sensor 17a). In this case, conditions are met that cause color mixing, so light amount adjustment is required.

In this embodiment, a filter 171 that blocks the light of the second light source 13b is provided for the first image sensor 17a. The filter 171 is provided, for example, by placing a filter that absorbs or reflects the light of the second light source 13b on the light receiving surface of the first image sensor 17a. This allows the first image sensor 17a to block almost all of the light from the second light source 13b and receive only the light of the first light source 13a.

On the other hand, the second image sensor 17b is configured to receive light from the first light source 13a and the second light source 13b, and has light receiving sensitivity not only in the wavelength region of the light from the second light source 13b but also in the wavelength region of the light from the first light source 13a.

The first image sensor 17a and the second image sensor 17b are located adjacent to or near each other, and the second image sensor 17b receives light from the other, i.e., the light from the first light source 13a.

The filter 171 is an example of a means for preventing the light of the second light source 13b from entering the first image sensor 17a. The avoidance means may be a means other than the provision of the filter 171, as long as the purpose can be achieved. For example, the second image sensor may be disposed in a position where the light of the first light source 13a does not enter (a position far from the first image sensor 17a).

With this configuration, the reading device 1 performs the following light intensity adjustment. The light intensity adjustment is performed as follows by the CPU 31 executing the light intensity adjustment program while using the memory 32 as necessary.

Figure 4 is a flow diagram showing an example of a first pattern of light intensity adjustment of the reading device 1. First, the CPU 31 turns on the first light source 13a with the reference light intensity Po1 set, and starts adjusting the light intensity of the first light source 13a (S101).

Next, the CPU 31 acquires the output Do1_1 of the first image sensor 17a at the reference light amount Po1 of the first light source 13a, and stores it at address 1 of the memory 32 (S102). Do1_1 is the reference data of the first image sensor 17a at the reference light amount Po1 of the first light source 13a.

Next, the CPU 31 acquires the output Do2_1 of the second image sensor 17b at the reference light amount Po1 of the first light source 13a, and stores it in address 2 of the memory 32 (S103). Do2_1 is the degree of color mixing of the first light source 13a with the second image sensor 17b.

Next, the CPU 31 turns off the first light source 13a (S104), calculates the light intensity value P1 that satisfies the light intensity condition of the first light source 13a, and sets it in the first light intensity setting unit 340a (S105). An example of the light intensity condition of the first light source 13a is P1 = Po1 x Tar1 / Do1_1. Tar1 shown in the light intensity condition is a predetermined light intensity adjustment target value. Here, the CPU 31 can release address 1 in order to read Do1_1 from the memory 32 to calculate the light intensity value P1. At this point, the light intensity adjustment of the first light source 13a is completed.

Next, the CPU 31 turns on the second light source 13b at the reference light amount Po2 and starts adjusting the light amount of the second light source 13b (S106).

Next, the CPU 31 acquires the output Do2_2 of the second image sensor 17b at the reference light amount Po2 of the second light source 13b, and stores it at address 1 of the memory 32 (S107). Do2_2 is the reference data of the second image sensor 17b at the reference light amount Po2 of the second light source 13b.

Next, the CPU 31 turns off the second light source 13b (S108), calculates the light intensity value P2 that satisfies the light intensity condition of the second light source 13b, and sets it in the second light intensity setting unit 340b (S109). An example of the light intensity condition of the second light source 13b is P2 = Po2 x (Tar2 - D2_1 x P1/Po1)/Do2_2. Tar2 shown in the light intensity condition is a predetermined light intensity adjustment target value. Here, the CPU 31 can free up addresses 1 and 2 to read Do2_1 and Do2_2 from the memory 32 to calculate the light intensity value P2. At this point, the light intensity adjustment of the second light source 13b is complete.

The location where Do1_1 and Do2_1 are stored is not limited to the memory 32 of the reading device 1, but may be an external memory outside the reading device 1.

By performing the first pattern of light intensity adjustment as described above, only addresses 1 and 2 are required for light intensity adjustment, making it possible to reduce the capacity of memory 32 without increasing the adjustment time for light intensity adjustment.

For combinations of light sources and image sensors that produce almost no color mixing, such as the combination of the second light source 13b and the first image sensor 17a, there is no need to acquire and store the degree of color mixing. Therefore, it is possible to omit the acquisition and storage of that amount of data, and even if the capacity of the memory 32 is reduced accordingly, it is possible to appropriately adjust the amount of light.

Figure 5 is a flow diagram showing an example of the second pattern of light intensity adjustment of the reading device 1. First, the CPU 31 turns on the first light source 13a at the reference light intensity Po1 and starts adjusting the light intensity of the first light source 13a (S201).

Next, the CPU 31 acquires the output Do2_1 of the second image sensor 17b at the reference light amount Po1 of the first light source 13a, and stores it at address 1 of the memory 32 (S202).

Next, the CPU 31 calculates the light intensity value P1 that satisfies the light intensity condition of the first light source 13a and sets it in the first light intensity setting unit 340a (S203).

Next, the CPU 31 turns off the first light source 13b (S204). This completes the light intensity adjustment of the first light source 13a.

Next, the CPU 31 turns on the second light source 13b with the reference light amount Po2 (S205). Next, the CPU 31 calculates the light amount value P2 that satisfies the light amount condition of the second light source 13b and sets it in the second light amount setting unit 340b (S206). Here, the CPU 31 can release address 1 because it reads Do2_1 from the memory 32 to calculate the light amount value P2.

Next, the CPU 31 turns off the second light source 13b (S207), and the light intensity adjustment of the second light source 13b is now complete.

As in the flow of the second pattern above, the image sensor output is read out and the light amount is set while the light source for adjusting the light amount is turned on, so the image sensor output serves as a substitute for memory. Therefore, with the flow of the second pattern, there is no need to store Do1_1 in memory, and it is possible to appropriately adjust the light amount with less memory capacity than the first pattern.

Figure 6 is a flow diagram showing an example of the third pattern of light intensity adjustment of the reading device 1. First, the CPU 31 turns on the first light source 13a at the reference light intensity Po1 and starts adjusting the light intensity of the first light source 13a (S301).

Next, the CPU 31 calculates the light intensity value P1 that satisfies the light intensity condition of the first light source 13a and sets it in the first light intensity setting unit 340a (S302). This completes the light intensity adjustment of the first light source 13a.

Next, the CPU 31 turns on the second light source 13b at the reference light amount Po2 (S303).

Next, the CPU 31 determines whether the output D2 of the second image sensor 17b satisfies D2 = Tar2 (S304).

If the output D2 does not satisfy D2=Tar2 (S304: No judgment), the CPU 31 increments the light intensity value set in the second light intensity setting unit 340b by a predetermined unit to increase the light intensity of the second light source 13b (S305). After that, the CPU 31 performs the judgment of S304 again. The number of units to be incremented may be one unit or multiple units.

When the output D2 satisfies D2 = Tar2 (S304: Yes judgement), the CPU 31 turns off the first light source 13a and the second light source 13b since the light intensity adjustment of the second light source 13b is completed (S306, S307).

As in the flow of the third pattern above, the first light source 13a is set to the target light intensity P1, and the light intensity of the second light source 13b is adjusted while the first light source 13a is turned on at the light intensity P1. This causes the second image sensor output when the light intensity of the second light source 13b is adjusted to include the mixed color component of the first light source 13a. By adjusting the light intensity in this manner, it becomes possible to appropriately adjust the light intensity without increasing the adjustment time for the light intensity adjustment and without storing the data in memory for light intensity adjustment, i.e., without increasing the memory capacity from that of a general reading device.

In the flow shown in FIG. 6, the light amount of the second light source 13b is adjusted by gradually increasing the light amount, but this is just one example, and other methods may be used as long as they can match the sensor output to the light amount adjustment target value. For example, Po2 may be set to a light amount such that D2≧Tar2, and the light amount may be gradually decreased. In addition, the light amount of the second light source 13b may be set by estimating the amount of color mixing that the first light source 13a causes on the second image sensor 17b from the light amount P1 after the light amount adjustment of the first light source 13a and the optical characteristics of the first light source 13a and the second image sensor 17b.

Figure 7 is a flow diagram showing an example of the fourth pattern of light intensity adjustment of the reading device 1. First, the CPU 31 turns on the first light source 13a at the reference light intensity Po1 and starts adjusting the light intensity of the first light source 13a (S401).

Next, the CPU 31 acquires the output Do1_1 of the first image sensor 17a at the reference light amount Po1 of the first light source 13a, and stores it at address 1 of the memory 32 (S402). Do1_1 is the reference data of the first image sensor 17a at the reference light amount Po1 of the first light source 13a.

Next, the CPU 31 calculates the light intensity value P1 that satisfies the light intensity condition of the first light source 13a and sets it in the first light intensity setting unit 340a (S403). Here, the CPU 31 can release address 1 because it reads Do1_1 from the memory 32 to calculate the light intensity value P1. At this point, the light intensity adjustment of the first light source 13a is complete.

Next, the CPU 31 turns on the second light source 13b at the reference light intensity Po2 and starts adjusting the light intensity of the second light source 13b (S404).

Next, the CPU 31 acquires the output Do2_2 of the second image sensor 17b at the reference light amount Po2 of the second light source 13b, and stores it at address 1 of the memory 32 (S405). Do2_2 is the reference data of the second image sensor 17b at the reference light amount Po2 of the second light source 13b.

Next, the CPU 31 determines whether the output D2 of the second image sensor 17b satisfies D2 = D2max (S406).

If the output D2 does not satisfy D2=D2max (S406: No), the CPU 31 determines whether the light output of the second light source 13b is the maximum output (S407).

If the light output of the second light source 13b is not the maximum output (S407: No judgment), the CPU 31 increments the light value set in the second light amount setting unit 340b by a predetermined unit to increase the light amount of the light source 13b (S408). After that, the CPU 31 performs the judgment of S406 again. The number of units to be incremented may be one unit or multiple units.

When the output D2 satisfies D2 = D2max (S406: Yes judgement) or the light output of the second light source 13b reaches the maximum output (S407: Yes judgement), the CPU 31 completes the light output adjustment of the second light source 13b and turns off the first light source 13a and the second light source 13b (S409, S410).

As in the flow of the fourth pattern above, the condition for ending the light intensity adjustment of the second light source 13b (the condition for satisfying the second light intensity adjustment) is to set the output D2 of the second image sensor 17b to not only the maximum output of the second light source 13b but also the saturation output value D2max of the second image sensor 17b, thereby adjusting the light intensity of the second light source 13b to the maximum light intensity within the range where the second image sensor 17b is not saturated.

Note that D2max does not necessarily have to be the saturation output value of the second image sensor 17b itself, but may be a value that includes a margin on the saturation output value in accordance with the amount of light from the light source that fluctuates with temperature changes due to heat generation from electronic devices, the stability of the sensor sensitivity, or the stability of the spectral characteristics of the optical element.

Figures 8 and 9 are diagrams illustrating the results of comparing images output from the image sensor when the maximum light intensity that does not saturate is not set (other than the fourth pattern) and when the maximum light intensity that does not saturate is set (fourth pattern).

Figure 8 shows an example of a manuscript. Figure 8 shows an example of a manuscript 400 that includes text 401 and an image 402.

9 is a comparison diagram of the output image 500 of the image sensor reading the original 400 shown in FIG. 8 when the maximum light amount that does not saturate is not set (FIG. 9(a)) and when it is set (FIG. 9(b)). In general, the more light incident on the sensor, the higher the S/N of the image. S/N is the signal-to-noise ratio, and the higher the S/N, the better the graininess of the image. In FIG. 9(a), the maximum light amount that does not saturate is not set, so the second image 500, which is the original image output from the second image sensor 17b, is an image with overall noise and graininess, and the text 501 and image 502 are of lower quality than the text 401 and image 402 of the original 400, making them difficult to reproduce. On the other hand, in FIG. 9(b), the maximum light amount that does not saturate is set, so the second image output from the second image sensor 17b is an image that is almost similar to the original 400, and has good reproducibility. In other words, by adjusting the amount of light from the second light source 13b to the maximum amount of light that does not saturate the second image sensor 17b, as used in the fourth pattern, it is possible to improve the image quality of the reading from the second image sensor 17b.

Example 1
In the first embodiment, an example was shown in which the first light source 13a and the second light source 13b are respectively used in different arbitrary wavelength bands, but as one example of the first embodiment, it is possible to use invisible light for the first light source and visible light for the second light source. The configuration of the processing unit of the reading device 1 according to the example 1 is shown below, and the usage form in that case is described.

Figure 10 is a diagram showing an example of the configuration of a processing unit that adjusts the light intensity of the reading device 1 according to an example of the first embodiment. As with Figure 2, Figure 10 shows the processing unit and the control target involved in light intensity adjustment when the CPU is given the light intensity adjustment function as an example, and other components of the reading device 1 are not shown. Also, in the configuration shown in Figure 10, the same components as in Figure 2 are given the same numbers. As for the other components, the components shown in Figure 2 are replaced with those for invisible light and visible light, respectively, and the correspondence between the configuration in Figure 10 and the configuration in Figure 2 is as follows:

In FIG. 10, the first light source 13a (see FIG. 2) is replaced with an invisible light source 43a, which is a light source of invisible light. In accordance with this replacement, the first light amount adjustment means 34a (see FIG. 2) is replaced with an invisible light amount adjustment means 44a, the first light amount setting unit 340a (see FIG. 2) is replaced with an invisible light amount setting unit 440a, and the first image sensor 17a (see FIG. 2) is replaced with an invisible light image sensor 47a.

The second light source 13b (see FIG. 2) is replaced with a visible light source 43b, which is a light source of visible light. In accordance with this replacement, the second light amount adjustment means 34b (see FIG. 2) is replaced with a visible light amount adjustment means 44b, the second light amount setting unit 340b (see FIG. 2) is replaced with a visible light amount setting unit 440b, and the second image sensor 17b (see FIG. 2) is replaced with a visible light image sensor 47b.

In the case of the reading device 1 according to the embodiment, it is possible to use the device in such a way that an image of visible light information and invisible light information from an original containing visible light information in the visible light wavelength range and invisible light information in the invisible light wavelength range is read in a single image read (e.g., simultaneous reading). The light amount adjustment process for suppressing color mixing is performed in one of the first to fourth patterns shown as examples in the first embodiment, and the following results are obtained.

Figure 11 is a comparison diagram of a document to be read and an output image output from an image sensor by reading the document in one go. Figure 11(a) is an example of a document containing visible light information and invisible light information. Figure 11(a) shows an example of a certificate 400 that contains text 401 and image 402 that can be read in the visible light wavelength range, and further contains invisible light information 403 that can be read in the invisible light range. Certificate 400 can be implemented, for example, in a business card, membership card, student ID, driver's license, passport, or My Number card. Text 401 is text information such as a name and address, image 402 is a face photograph, and invisible light information 403 is information such as a hidden picture or logo.

When the invisible light source 43a and the visible light source 43b illuminate the certificate 400 with light, the visible light image sensor 47b outputs a visible light image 510 shown in FIG. 11(b) as the second image. Also, the invisible light image sensor 47a outputs an invisible light image 520 shown in FIG. 11(c) as the first image.

Visible light image 510 includes text 511 and image 512 obtained by reading text 401 and image 402 of the visible light information. In addition, visible light image 510 has an image quality close to that of certificate 400 because color mixing caused by invisible light is appropriately suppressed by the light amount adjustment shown in the first embodiment.

The invisible light image 520 includes an image 523 in which the invisible light information 403 has been read, and color mixing is also suppressed.

(Modification 1 of the first embodiment)
Fig. 12 is a diagram showing an example of the configuration of a processing unit that adjusts the light amount of the reading device 1 according to Modification 1. In the reading device 1 shown in Fig. 12, the invisible light amount adjustment means 44a in the configuration shown in Fig. 10 is further provided with a light amount adjustment target value selection unit 441a of the invisible light source as an example of a "selection unit".

The invisible light source light intensity adjustment target value selection unit 441a sets the invisible light source 43a light intensity adjustment target value Tar1 to a light intensity Tar1bw at which the hidden picture or logo in the invisible light information 403 can be visually recognized. Since the fineness of the hidden picture or logo and the ease of recognition by the user vary depending on the amount of light, a setting that is easy for each user to recognize, that is, a luminance difference with respect to the subject skin of the invisible information (skin of the certificate 400) is determined in advance and an optimal light intensity adjustment target value is set. When the visible light information 403 and the user who uses it are fixed and do not need to be changed, one light intensity adjustment target value for the invisible light source 43a is determined. In that case, a fixed light intensity adjustment target value is set in advance from the invisible light source light intensity adjustment target value selection unit 441a to the invisible light intensity setting unit 440a.

On the other hand, when the visible light information 403 or the user is not fixed and the combination of the visible light information 403 and the user changes, the invisible light source light intensity adjustment target value selection unit 441a has the user select a light intensity adjustment target value and sets it in the invisible light intensity setting unit 440a. For example, the invisible light source light intensity adjustment target value selection unit 441a stores multiple light intensity adjustment target values in a memory or the like, and accepts the selection of a light intensity adjustment target value suitable for the user from among the stored light intensity adjustment target values by the user inputting an operation from a touch panel, operation button, or the like.

Figure 13 is a flow diagram showing an example of light intensity adjustment of the reading device 1 according to the first modified example. The flow shown in Figure 13 is a flow in which S501 is added before S101 of the flow shown in Figure 4. In the flow shown in Figure 13, the CPU 31 first sets the light intensity adjustment target value Tar1 of the invisible light source 43a to the above-mentioned Tar1bw. The subsequent steps of S502 to S510 correspond to S101 to S109 in Figure 4, and light intensity adjustment is performed in the same steps as S101 to S109, except that Tar1 is replaced by Tar1bw. The explanation from S502 onwards is omitted as it would be repetitive.

Figure 14 is a comparison diagram of a document to be read and an output image output from an image sensor by reading the document in one go. Figure 14 (a) is the certificate 400 in Figure 11 (a).

Generally, visible light information includes black ballpoint pen or black dye ink that transmits infrared light. If the visible light information of the certificate 400 is written with such black coloring material, normal adjustment of the amount of visible light and invisible light will result in the amount of invisible light being adjusted to be greater or smaller than the appropriate amount of light. If simultaneous reading of visible light and invisible light (infrared light in this case) is performed in such a state, when the amount of invisible light is large, the visible light image 510, as shown in FIG. 14(b1), can read text 511 and image 512 with almost the same brightness as the original, that is, text 401 and image 402 of the certificate 400. On the other hand, as for the invisible light information 403 of the certificate 400, as shown in FIG. 14(c1), the difference in brightness with the background image of the certificate 400 is small, and the image of the invisible information 403 cannot be seen.

When the amount of invisible light is small, as shown in FIG. 14(c2), the invisible light image 523 has a clear difference in brightness between the background image of the certificate 400 and the image of the invisible information 403, making it easy to see. On the other hand, as shown in FIG. 14(c1), the text 511 and image 512 in the visible light image become brighter than the original, that is, the text 401 and image 402 of the certificate 400, due to color mixing caused by invisible light in the visible light sensor, making them difficult to see.

Therefore, a light intensity adjustment flow is implemented. When the light intensity adjustment flow according to the first modification is implemented, as shown in FIG. 14(b3), the effects of color mixing in visible light image 510 are suppressed and text 511 and image 512 are read at a brightness close to that of the original, i.e., close to that of certificate 400. Also, as shown in FIG. 14(c3), the amount of light in invisible light image 520 is small, so the brightness difference between invisible image 523 and the background image of certificate 400 is smaller than in FIG. 14(c2), but it is still read at a visible level.

As described above, for example, when the invisible light information on a document is a hidden picture or logo, the read image of the invisible light information must also be visible to the human eye. If the light intensity of the invisible light source is too small, the background image of the document becomes dark, the difference in luminance with the invisible light image becomes small, and the shape of the picture or logo becomes difficult to recognize. Therefore, the required light intensity of the invisible light source is determined by the visibility of the invisible light image. Therefore, the light intensity adjustment target value can be set by the invisible light source light intensity adjustment target value selection unit based on the required light intensity.

As described above, the amount of light from the invisible light source is adjusted to a level at which invisible information is visible, and the amount of invisible light is not increased more than necessary. This makes it possible to suppress color mixing with the visible light sensor due to invisible light, improving the image quality of the visible light image.

(Variation 2)
As a second modification, an example in which two-dimensional code information is used as invisible information will be described.

Figure 15 is a diagram showing an example of a certificate that uses two-dimensional code information as invisible information. The certificate 400 shown in Figure 15 includes two-dimensional code information 404 as invisible information. As an example, the two-dimensional code information 404 displays a QR code (registered trademark).

One of the necessary requirements for decoding a QR code is the S/N ratio of the image. For this reason, the amount of light from the invisible light source must be set to an amount that provides an image level S/N that allows the QR code to be decoded. Since the S/N ratio required for decoding is determined by the cell size of the QR code, the amount of invisible light required is determined by the cell size of the QR code, and so the target value Tar1SN for adjusting the light amount of the invisible light source is determined.

As the S/N required for decoding changes depending on the cell size of the QR code, the invisible light source light intensity adjustment target value selection unit 441a stores the light intensity adjustment target values for each cell size in a memory or the like, and has the user select the cell size of the QR code from a touch panel, operation button, etc., to recognize the cell size.

In addition, if the cell size of the QR code to be read is determined by the type of subject, such as a certificate, the invisible light source light intensity adjustment target value selection unit 441a may recognize the cell size by having the user input the type of subject from the correspondence table. The correspondence table is stored in a memory or the like as a table that associates the type of subject with the cell size of the QR code. Furthermore, if the QR code to be read is fixed and there is no need to change the cell size, the invisible light source light intensity adjustment target value is determined as one without needing to be set. In this case, a fixed light intensity adjustment target value that matches the cell size of the QR code is set in advance by the invisible light source light intensity adjustment target value selection unit 441a to the invisible light intensity setting unit 440a.

Figure 16 is a flow diagram showing an example of light intensity adjustment of the reading device 1 according to the second modification. The flow shown in Figure 16 is the same as that shown in Figure 13, except that the setting of Tar1bw in S501 is replaced with Tar1SN. Apart from replacing Tar1bw with Tar1SN, steps S601 to S610 adjust the light intensity in the same manner as steps S501 to S510. As this would be a repetition of the explanation of steps S501 to S510, an explanation of the procedure will be omitted here.

As described above, the target light intensity adjustment value Tar1 of the invisible light source is set to Tar1SN, which satisfies the S/N ratio that is a necessary requirement for decoding a two-dimensional code. This makes it possible to adjust the light intensity of the invisible light source to an intensity that allows the invisible two-dimensional code to be decoded. In addition, because the invisible light intensity is not increased more than necessary, color mixing in the visible light sensor due to invisible light can be suppressed, improving the image quality of the visible light image.

(Variation 3)
As a third modification, an example in which one-dimensional barcode information is used as invisible information will be described.

Figure 17 is a diagram showing an example of a certificate that uses one-dimensional barcode information as invisible information. The certificate 400 shown in Figure 17 includes one-dimensional barcode information 405 as invisible information.

A necessary requirement for decoding a one-dimensional barcode is the MTF (Modulation Transfer Function) of the image. MTF is one of the indices that indicate the reading resolution of an image. If the amount of light from the invisible light source is too small, the background image of the certificate 400 will become dark and the MTF will decrease. For this reason, a certain amount of light is required. In addition, the MTF (readable level) required to read a barcode is determined by the width of the narrow bar of the barcode. For this reason, the amount of invisible light required is determined by the width of the narrow bar of the barcode, and the target value Tar1MTF for adjusting the amount of invisible light from the invisible light source is determined.

Because MTF involves optical image blur, the condition is stricter than the luminance difference between the background image and the invisible light image.

As such, since the MTF required to read a barcode changes depending on the width of the narrow bar of the barcode, the invisible light source light intensity adjustment target value selection unit 441a stores the light intensity adjustment target values for each narrow bar width in a memory or the like, and has the user select the narrow bar width from a touch panel, operation button, etc., to recognize the narrow bar width of the barcode to be read.

If the narrow bar of the barcode to be read is determined by the type of subject, such as a certificate, the invisible light source light intensity adjustment target value selection unit 441a may recognize the width of the narrow bar of the barcode by having the user input the type of subject from the correspondence table. The correspondence table is stored in a memory or the like as a table that associates the type of subject with the width of the narrow bar of the barcode. Furthermore, if the width of the narrow bar of the barcode to be read is fixed and does not need to be changed, the invisible light source light intensity adjustment target value is determined as one without needing to be set. In this case, a fixed light intensity adjustment target value that matches the width of the narrow bar of the barcode in advance is set from the invisible light source light intensity adjustment target value selection unit 441a to the invisible light intensity setting unit 440a.

Figure 18 is a flow diagram showing an example of light intensity adjustment of the reading device 1 according to the third modified example. The flow shown in Figure 18 is obtained by replacing the setting of Tar1bw in S501 of the flow shown in Figure 13 with Tar1MTF. Apart from replacing Tar1bw with Tar1MTF, S701 to S710 adjust the light intensity in the same manner as S501 to S510. Since this would be a repetition of the explanation of S501 to S510, the explanation of the procedure will be omitted here.

As described above, the light intensity adjustment target value Tar1 of the invisible light source is set to Tar1MTF, which satisfies the MTF required for decoding a one-dimensional barcode. This makes it possible to adjust the light intensity of the invisible light source to an intensity that allows the invisible one-dimensional barcode to be decoded. In addition, because the invisible light intensity is not increased more than necessary, color mixing in the visible light sensor due to invisible light can be suppressed, improving the image quality of the visible light image.

(Variation 4)
Fig. 19 is a diagram showing an example of the configuration of a processing unit that adjusts the amount of light in the reading device 1 according to the modified example 4. The reading device 1 shown in Fig. 14 further includes an invisible light component removal means 51 and an object information extraction unit 52 in addition to the configuration shown in Fig. 12. The invisible light component removal means 51 is an example of a "removal means".

The invisible light component removal means 51 removes invisible light components from the visible light image sensor output. The invisible light component removal means 51 holds the visible light image sensor output when only the invisible light source is turned on, and removes the invisible light components by subtracting the visible light image sensor output when only the invisible light source is turned on from the visible light image sensor output when the visible light source and the invisible light source are turned on simultaneously.

The object information extraction unit 52 extracts object information from the read image. Object information is information on whether an object on the read image has elements that make up an image, such as whether it has the characteristics of text, the characteristics of halftone dots, whether it is colorless or colored, etc. The extracted object information is generally used to optimize the image processing applied to images read by copiers, etc. For example, if the object is determined to be text, it is processed to emphasize the edges so that it looks clearer, if it is determined to be a pattern, it is smoothed so that it looks smoother, and if it has no characteristics, it is processed to make it uniform in value with the surroundings as background.

Here, the visible light image sensor output and the invisible light image sensor output each have different optical shot noise, so when the invisible light components are removed, the noise of the invisible light image sensor is transferred to the visible light image sensor output. The greater the amount of light, the greater the optical shot noise, so the greater the amount of invisible light, the greater the amount of noise transferred when the invisible light components are removed, and the lower the S/N ratio of the visible light image.

When the S/N ratio decreases and noise in the visible light image increases, it affects the extraction of object information. For example, text and background areas may be mistaken for halftone dots. Therefore, the light intensity adjustment target value is set so that the image after the invisible light components are removed is at a level that makes it possible to extract object information.

Figure 20 is a comparison diagram of the document to be read and the output image output from the image sensor by reading the document in one go.

As mentioned above, a decrease in S/N and an increase in noise in the visible light image affects the extraction of object information. For example, text and background areas may be mistakenly determined to be halftone dots. In this case, as shown in FIG. 20(c1), the text area 621 may be smoothed, or the background area may not be removed and a noise image may remain, degrading the quality of the output image. To prevent this, the visible light image must have an S/N ratio that is equal to or higher than the minimum required to extract object information.

Due to the relationship between the amount of invisible light and the required S/N of the visible light image, the upper limit of the amount of light from the invisible light source is determined by the S/N of the visible light image, and the target value for adjusting the amount of light from the invisible light source is determined.

By adjusting the amount of invisible light so as to obtain the minimum S/N ratio required for extracting object information from a visible light image, it is possible to suppress a decrease in the S/N ratio of the visible light image as shown in FIG. 20(b2), and it is possible to adjust the amount of light so as not to erroneously determine the extraction of object information from the visible light image.

(When using a general image sensor)
General silicon image sensors are sensitive in the near-infrared range (approximately 750 nm to 1100 nm). Therefore, it is possible to use general-purpose image sensors that have been used in the past without having to prepare separate image sensors for visible and invisible light.

Figure 21 is a diagram showing an example of the configuration of a processing unit that adjusts the amount of light in the reading device 1 when a general-purpose image sensor is used. In the configuration shown in Figure 21, the configuration shown in Figure 10 that corresponds to invisible light is replaced with one that corresponds to infrared light. The correspondence between the configuration in Figure 21 and the configuration in Figure 10 is as follows.

In FIG. 21, the invisible light source 43a (see FIG. 10) has been replaced with an infrared light source 53a. With this replacement, the invisible light amount adjustment means 44a (see FIG. 10) has been replaced with an infrared light amount adjustment means 54a, the invisible light amount setting unit 440a (see FIG. 10) has been replaced with an infrared light amount setting unit 540a, and the invisible light image sensor 47a (see FIG. 10) has been replaced with an infrared light image sensor 57a.

Here, the visible light image sensor 47b and the infrared light image sensor 57a use commonly used silicon image sensors.

Figure 22 shows the spectral characteristics of a silicon image sensor. In Figure 22, the horizontal axis shows the wavelength (nm) and the vertical axis shows the relative intensity, showing a characteristic graph of the light sensitivity in each wavelength range.

As shown in Figure 22, RED, GREEN, and BLUE light show high sensitivity in the wavelength range of each color. IR (infrared) light shows high sensitivity in the infrared region.

If such a silicon image sensor is used, it can be implemented with a simple configuration by providing a filter 171 that cuts visible light in the range of the pixels that read invisible light.

(Reference subject)
In the above, an example has been shown in which the reflected light of the first light source 13a is incident on the first image sensor 17a, and the reflected light of the second light source 13b is incident on the second image sensor 17b, as in the example shown in Fig. 3. Note that a member that reflects the light from the first light source 13a and the light from the second light source 13b to the first image sensor 17a and the second image sensor 17b may be a reference subject that is generally provided in the reading device 1.

Figure 23 is a diagram showing an example of a configuration including a reference subject. As shown in Figure 23, a member that reflects light from the first light source 13a and the second light source 13b to the first image sensor 17a and the second image sensor 17b is taken as the reference subject 260 provided in the reading device 1. The reference subject 260 is, for example, a white reference member. By using such a reference subject provided in a general reading device, it becomes possible to stably acquire data and further improve the accuracy of light amount adjustment.

Second Embodiment
Fig. 24 is a diagram showing an example of a configuration of an image forming apparatus according to the second embodiment. In Fig. 24, an image forming apparatus 2 is an image forming apparatus generally called a multifunction peripheral (MFP) having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function.

The image forming device 2 has a reading device main body 10 and an ADF 20, which are reading devices, and an image forming unit 103 below them.

The ADF 20 feeds an original document, reads the side to be read at the reading position (reading window), and discharges the document onto the discharge tray. The reading device main body 10 reads the side of the original document to be read at the reading position. The ADF 20 is the ADF 20 according to the first embodiment (see FIG. 1), and the reading device main body 10 is the reading device main body 10 according to the first embodiment (see FIG. 1). The ADF 20 and the reading device main body 10 have already been described in the first embodiment. Therefore, further description of the ADF 20 and the reading device main body 10 will be omitted.

In FIG. 24, the image forming unit 103 has its external cover removed to explain its internal configuration so that the internal configuration can be seen. The image forming unit 103 prints the document image read by the reading device main body 10. The image forming unit 103 has a manual feed roller 104 for manually feeding recording paper, and a recording paper supply unit 107 for supplying recording paper. Here, recording paper is an example of a "medium". The recording paper supply unit 107 has a mechanism for feeding recording paper from a multi-stage recording paper feed cassette 107a. The supplied recording paper is sent to the secondary transfer belt 112 via a registration roller 108.

The toner image on the intermediate transfer belt 113 is transferred to the recording paper transported on the secondary transfer belt 112 in the transfer section 114.

The image forming unit 103 also includes an optical writing device 109, tandem imaging units (Y, M, C, K) 105, an intermediate transfer belt 113, and the secondary transfer belt 112. Through an image creation process by the imaging units 105, the image (first image or second image) written by the optical writing device 109 is formed as a toner image on the intermediate transfer belt 113.

Specifically, the imaging unit (Y, M, C, K) 105 has four rotatable photosensitive drums (Y, M, C, K), and is provided with imaging elements 106 including a charging roller, a developing unit, a primary transfer roller, a cleaner unit, and a static eliminator around each photosensitive drum. The imaging elements 106 function for each photosensitive drum, and the image on the photosensitive drum is transferred onto the intermediate transfer belt 113 by each primary transfer roller.

The intermediate transfer belt 113 is stretched across a drive roller and a driven roller in the nip between each photosensitive drum and each primary transfer roller. The toner image primarily transferred onto the intermediate transfer belt 113 is secondarily transferred to the recording paper on the secondary transfer belt 112 by the secondary transfer device as the intermediate transfer belt 113 moves. The recording paper is transported to the fixing device 110 by the secondary transfer belt 112, where the toner image is fixed onto the recording paper as a color image. The recording paper is then discharged to a paper output tray outside the machine. In the case of double-sided printing, the recording paper is turned over by the reversing mechanism 111, and the inverted recording paper is sent onto the secondary transfer belt 112.

Note that the image forming unit 103 is not limited to one that forms images using the electrophotographic method described above, but may also form images using an inkjet method.

Although the embodiments and modifications of the present invention have been described above, the embodiments and examples are presented as examples and are not intended to limit the scope of the invention. These novel embodiments and examples can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and examples are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

REFERENCE SIGNS LIST 1 Reading device 13a First light source 13b Second light source 17a First image sensor 17b Second image sensor 31 CPU
32 Memory 34a First light amount adjustment means 34b Second light amount adjustment means 171 Filter 310 Indication means 311 Setting means 340a First light amount setting section 340b Second light amount setting section

JP 2006-237896 A

Claims (15)

A first light source;
a second light source having a different wavelength from that of the first light source;
an instruction means for instructing turning on and off the first light source and the second light source;
a first light amount adjusting means for adjusting the light amount of the first light source based on a first light amount value;
a second light amount adjusting means for adjusting the light amount of the second light source based on a second light amount value;
a first image sensor that receives light from the first light source reflected from a subject ;
a second image sensor that receives the light of the first light source and the light of the second light source reflected from the subject;
a setting means for setting a light amount value that satisfies a first light amount condition based on output data output from the first image sensor while the first light source is turned on as the first light amount value, and setting a light amount value that satisfies a second light amount condition based on output data output from the second image sensor while the first light source is turned on as the second light amount value;
A reading device comprising: The setting means is
holding in a memory the output data output from the first image sensor and the output data output from the second image sensor in a lighting state of the first light source;
setting a light amount value calculated from the first light amount condition using the output data of the first image sensor stored in the memory as the first light amount value;
releasing an area that has held the output data of the first image sensor, and holding the output data output from the second image sensor in a lighting state of the second light source;
setting a light amount value calculated from the second light amount condition using the output data of the second image sensor in a lighting state of the first light source and the output data of the second image sensor in a lighting state of the second light source as the second light amount value;
2. The reading device according to claim 1, wherein the reading device is a reading device for reading a document. The setting means is
The first light amount value is set in a state in which the first light source is turned on,
The second light amount value is set in a state in which the second light source is turned on.
2. The reading device according to claim 1, wherein the reading device is a reading device for reading a document. The setting means is
The second light amount value is set in a state where the first light source is turned on with the light amount set as the first light amount value.
4. The reading device according to claim 3, The setting means is
the second light amount value is set within a range of light amount that does not cause saturation of an image in the second image sensor;
5. A reading device according to claim 1, wherein the reading device is a reading device for reading a document. The second light source is a light source in a visible light wavelength range, and the first light source is a light source in an invisible light wavelength range that is a wavelength range different from visible light.
A reading device according to any one of the preceding claims. a selection unit configured to receive a setting of a visibility level of the read image in the invisible light wavelength range output from the first image sensor,
the setting unit sets a light amount value that satisfies a light amount adjustment target value corresponding to the visibility level accepted by the selection unit as the first light amount value.
7. The reading device according to claim 6, Further, a selection unit is provided that accepts a setting of a level at which the two-dimensional code in the invisible light wavelength range output from the first image sensor can be decoded,
the setting means sets a light amount value that satisfies a light amount adjustment target value corresponding to a decodable level accepted by the selection unit as the first light amount value.
7. The reading device according to claim 6, a selection unit configured to receive a setting of a level at which the barcode in the invisible light wavelength range output from the first image sensor can be read;
the setting unit sets a light amount value that satisfies a light amount adjustment target value corresponding to a barcode readable level received by the selection unit as the first light amount value.
7. The reading device according to claim 6, a removing means for removing a component of light of the first light source from an output image of the second image sensor;
an object information extracting means for extracting object information from the output image;
Further equipped with
The setting means is
a light amount value of the first light source is set to a level at which object information can be extracted from an image after the light components have been removed by the removing means;
The reading device according to any one of claims 7 to 9. The first light source is a light source in the infrared wavelength range.
11. Reading device according to any one of claims 6 to 10, characterized in that the first image sensor and the second image sensor receive reflected light from a reference object by the first light source and the second light source, thereby adjusting the light amounts of the first light source and the second light source;
12. Reading device according to any one of the preceding claims. a means for preventing light of the second light source reflected from the object from being incident on the first image sensor;
13. Reading device according to any one of the preceding claims. A reading device according to any one of claims 1 to 13,
an image forming unit that forms on a medium an output image of the first image sensor or the second image sensor read from the subject with the light amount set by the setting means;
An image forming apparatus comprising: A method for suppressing color mixing between a first image sensor that receives light from a first light source reflected from an object, and a second image sensor that receives light from the first light source reflected from the object and light from a second light source having a different wavelength from that of the first light source, comprising:
setting a light amount value that satisfies a first light amount condition based on output data output from the first image sensor in a state where the first light source is turned on as a first light amount value;
setting a light amount value that satisfies a second light amount condition based on output data output from the second image sensor in a state where the first light source is turned on as a second light amount value;
adjusting the amount of light of the first light source based on the first light amount value;
adjusting the amount of light of the second light source based on the second light amount value;
The method includes:

Images